Single multi-electrode electron tube having a disc shaped ceramic stem with a recessed portion in one face thereof, said recess portion having a metal layer thereon



p 27, 1956 YOSHIO MURATA 3,275,877

SINGLE MULTI-ELECTRODE ELECTRON TUBE HAVING A DISC SHAPED CERAMIC STEM WITH A RECESSED PORTION IN ONE FACE THEE SAID RECESS PORTION HAVING A METAL LAYER THERE Filed Jan. 28, 1963 2 Sheets-Sheet 1 Fig.

illliildn 2349H m m w I I I rll I [ll INVENTOR Y sHlo muRHTH HTTDRNEY p 7. 1965 YOSHIO MURATA -ELECTRODE ELECTRON TUBE HAVING A DISC SHA 3,275,877 PED CERAMIC EOF, SAID PORTION HAVING A METAL LAYER THEREON SINGLE MULTI STEM WITH A RECESSED PORTION IN ONE FACE THER RECESS Filed Jan. 28. 1963 2 Sheets-Sheet 2 Fig. 6

Fig.7

Fig.4

Fig.8

Fig.5

INVENTOR YosHlo muRflTH BY= 1&2 7n.

ATTORNEY United States Patent SINGLE MULTI-ELECTRODE ELECTRON TUBE HAVING A DISC SHAPED CERAMIC STEM WITH A RECESSED PORTION IN ONE FACE THEREOF, SAID RECESS PORTION HAVING A METAL LAYER THEREON Yoshio Murata, Chiba, Japan, assignor to Hitachi Ltd., Chiyoda-ku, Tokyo, Japan, a corporation of Japan Filed Jan. 28, 1963, Ser. No. 254,289

Claims priority, application Japan, Jan. 31, 1962, 37/ 3,265; Feb. 24, 1962, 37/8,852; Mar. 9, 1962, 37/ 11,090, 37/ 11,091, 37/ 11,092, 37/ 11,093

9 Claims. (Cl. 313-.-250) The present invention relates to multi-electrode electron tubes of the type having a ceramic stem and is intended to provide an improved electrode-supporting structure for the type of multi-ele'ctrode electron tube.

Conventionally, multi-electrode electron tubes of the type described, which will be referred to herein as ceramic electron tube, have an electrode-supporting structure including electrode supports secured to the ceramic stem of the tube for supporting the electrodes thereof, which are soldered to the flanges, secured to the respective supports also by soldering. With this structure, each of the electrodes is customarily supported by a lead and two of said supports. This necessitates the use of a considerable number of leads and supports. Therefore, with conventional multi-electrode electron tubes, the ceramic stem has been made in a substantial size or difliculties have been met in assembling the mounting structure.

Moreover, with electron tubes such as tetrodes and pentodes usable at radio frequencies, it is required to minimize the inter-electrode capacitance between the plate and the control grid. However, with the structure as described above, there exists a substantial capacitive couple within the ceramic stem, rendering the structure inappropriate for use at radio frequencies.

The present invention has overcome these deficiencies of the conventional electrode-supporting structure and has for its object to provide a ceramic multi-electrode electron tube having an improved electrode-supporting structure in which a multiplicity of electrodes are firmly supported by a limited number of posts or supports and a high degree of inter-electrode shielding is effectively attained.

The foregoing and other objects, features and advantages of the invention will become apparent from the following description when taken in conjunction with the accompanying drawing, which illustrates a few embodiments of the invention and in which: 7

FIG. 1 is a vertical cross-section of a multi-electrode electron tube embodying the present invention;

FIG. 2 is a plan view of the ceramic stem employed in the embodiment;

FIG. 3 is a cross-section taken along the line AA' in FIG. 2;

FIGS. 4 and 5 are a cross-sectional and a plan view, respectively of the ceramic spacer also employed in the embodiment shown in FIG. 1;

FIG. 6 is a vertical cross-section of another embodiment of the invention; and

FIGS. 7 and 8 are a cross-sectional and a plan view of the ceramic spacer employed in the embodiment shown in FIG. 6.

Referring to the drawing and particularly to FIG. 1, the single-end type ceramic electron tube illustrated includes a heater element 1, a cathode 2, a control grid 3, a screen grid 4, a plate 5, a ceramic spacer 6 formed with an opening for receiving the plate 5, a cathode flange 7, and a control grid flange 8. The ceramic spacer 6 is metallized as indicated at 9 and 10. One of the metallized areas 9 extends over the bottom surface of the spacer 6 along a major portion of its outer periphery while the other metallized area 10 extends over the bottom surface of the spacer along the whole of its inner periphery, as clearly shown in FIGS. 4 and 5. The two metallized areas 9 and 10 are spaced apart from each other, as clearly seen in FIG. 5. A ceramic stem 12 is provided which has one or both of the opposite faces recessed as indicated at 20. The recessed area 20 has a configuration as indicated by the hatching in FIG. 2 and is metallized.

Reference numeral 11 indicates a screen grid flange;

' 13 a heater lead; 14 a cathode lead; 15 a cathode support;

16 a control grid lead; 17 a control grid support; and 18 a screen grid lead extending through and in electric contact with the recessed metallized area 20 on the ceramic stem 12. The screen grid lead 18 is connected at the top with the screen grid flange 11, which is soldered to one of the metallized surface areas 9 on the ceramic spacer 6. A plate lead 19 is soldered to the other metallized area 10 on the spacer 6. An enclosure 21 is soldered to the peripheral face of the ceramic stem 12 which is also metallized as indicated at 22.

As described above, in this structure according to the present invention, the plate '5 and screen grid flange 11 are soldered to the respective metallized areas 10 and 9 on the spacer 6 with the screen grid 4 soldered to the flange 11. The screen grid 4 and plate 5 are thus formed integral with each other through the medium of the spacer -6 and can be supported as a unit by the ceramic stem thereby reducing the number of supports required. Also, since as described the screen grid lead 18 is connected to the metallized area 20 on the ceramic stem 12, the metallized area 20 is maintained at the screen potential serving IHS a shield between the control grid lead 16 and the plate lead 19. It will be appreciated from the foregoing that the single-end type multi-electrode electron tube according to the invention is simple in construction, compact and sturdy.

Additionally, it will be understood that the cathode lead 14 in place of the screen grid lead 18 may be connected with the metallized area 20 on the stem to maintain the 'area 20 at the cathode potential for the same shielding purpose.

Referring next to FIG. 6, which illustrates another embodiment of the invention, the electron tube illustrated includes a cathode 2, a control grid 3, a screen grid 4, a suppressor grid 5, a plate 6, an annular ceramic spacer 7 having a central opening through which the control grid 3 extends, and a cathode flange 8. Part of the surface of the ceramic spacer 7 is metallized as indicated at 9 and 10. As clearly shown in FIGS. 7 and 8, one of the metallized areas 9 extends over the peripheral Wall surface of the central opening and a portion of the bottom surface of the spacer while the other metallized area 10 extends over the bottom surface of the spacer along a majority of its outer periphery. The control grid 3 and the screen grid flange 11 are electrically separated from each other, being secured to the metallized areas 9 and 10 on the spacer 7, respectively, by soldering. Reference numeral 12 indicates a plate flange and 13 a ceramic stern having one or both of the opposite faces recessed and metallized in the same manner as with the spacer employed in the first embodiment and shown in FIGS. 2 and 3. Reference numeral 14 indicates a heater lea-d; 15 a cathode lead; 16 a cathode support; 17 a control grid lead connected to one of the metallized areas 9 on the spacer 7; 18 a screen grid lead soldered to the other metallized area 10; 19 a plate lead; and 24 a plate support. An enclosure 21 is soldered to the peripheral face of the ceramic stem 12 which is also metallized as indicated at 22.

In this structure, the control and screen grids are formed integral with each other as in the structure of the first embodiment shown in FIG. 1, providing the same advantageouseifects as those obtained in the latter.

Having described a few embodiments of the invention, it is not to be limited to the details set forth but itis to be accorded the full scope of the appendant claims.

What is claimed is:

1. A single-end multi-electrode electron tube comprising a disc-shaped ceramic stem having a recessed portion in one face thereof, said recessed portion having a metal layer over the entire surface thereof,

a plurality of vacuum tube electrodes including at least a control grid, screen grid and plate electrode,

supporting means including supports and electrical leads for supporting said electrodes above said ceramic stem,

a ceramic spacer having a pair of isolated metal layers on one surface thereof, two adjacent ones of said electrodes being secured to respective metal layers on said ceramic spacer,

the electrical lead connected to the one of said two adjacent electrodes interposed between the remaining electrodes of said control grid, screengrid and plate:

electrode passing through said ceramic stern in the recessed portion thereof and coming into electrical contact with said metal layer on said ceramic stem, the electrical'leads connected to said remaining electrodes passing through the portion of the ceramic stem isolated from the metal layer thereon. 2. A single-end multi-electrode tube as defined in claim 1 wherein said two adjacent ones of said electrodes secured to respective metal layers on said ceramic spacer on said screen grid and said plate electrode, and the electrical lead passing through the metal layer in the recessed portion of said ceramic stem is connected to said screen grid.

3. A single-end multi-electrode tube asdefined in claim 1 wherein said two adjacent ones of said electrodes secured to respective metal layers on said ceramic spacer are said screen grid and said control grid, and the electrical lead passing through the metal layer in the recessed portion of said ceramic stem is connected to saidscreen grid.

4. A single-end multi-electrode tube as defined in claim 1 further including a metal enclosure surrounding said ceramic stem and said electrodes, said ceramic stem having a second metal layer on the peripheral face thereof in contact with said metal enclosure.

5. A single-end multi-electrode electron tube comprisa disc shaped ceramic stem having a recessed portion in one face thereof, said recessed portion having a metal layer thereon, a plurality of vacuum tube electrodes including a cathode, a control grid, screen grid and plate electrode, supporting means including supports and electrical leads for supporting said electrodes on said ceramic stem,

a ceramic spacer having a pair of isolated metal layers on one surface thereof, two adjacent ones of said electrodes being secured to respective metal layers on said ceramic spacer,

said cothode being connected via an electricallead to the metal layer on said ceramic stem,

6. A single-end multi-electrode electron tube comprisa disc-shaped ceramic stem having a recessed portion in one face thereof, said recessed portion having a metal layer over the entire surface thereof,

a plurality of vacuum tube electrodes including a cathode, control grid, screen, grid and plate electrode mounted concentrically,

supporting means including a supportland an electrical lead for each of said cathode and said control grid, said supporting means supporting said electrodes upon said ceramic stem, and I a ceramic spacer having a'pair of isolated metal layers on one surface thereof connected respectively to said screen grid and said plate electrode, said supporting means further including a pair' of electrical leads connected respectively to said screen grid and said plate electrodeand serving as the sole support for said elements on said ceramic stem, the lead connected to said screen grid being, in electrical contact with the metal layer in the recess portion of said ceramic stem.

'7. A single-end multi-elect-rode electron tube comprising. a disc-shaped ceramic stem having a recessed portion in one face thereof, said recessed portion having a metal layer over the entiresurface thereof,

a plurality of vacuum tube electrodes including a cathode, control grid, screen grid and plate electrode mounted concentrically,

supporting means including a support and an electrical lead for each of said cathode and said plate elec-- trode, said supporting means supporting said elecr trodesupon said ceramic stem, and

a ceramic spacer having a pair of isolated metal layers on one surface thereof connected respectively to said screen grid and'said control grid,

said supporting means further including a pair of elec.-;

9. A single-end multi-electrode tube as defined in claim 7 wherein said ceramic spacer is in the form of a ring and the metal layers thereon are arcuate in shape with at least one layer extending onto the inner surface of thering.

References Cited'by the Examiner UNITED; STATES PATENTS 2,248,558 7/1941 Schlesinger 313-250 2,719,185 9/1955 Sorget a1 313-256 X 2,899,590 8/1959 Sorg et al 313- 250 JOHN W. HUCKERT, Primary Examiner.: A J, JAMES, Assistant Examiner. 

1. A SINGLE-END MULTI-ELECTRODE ELECTRON TUBE COMPRISING A DISC-SHAPED CERAMIC STEM HAVING A RECESSED PORTION IN ONE FACE THEREOF, SAID RECESSED PORTION HAVING A METAL LAYER OVER THE ENTIRE SURFACE THEREOF, A PLURALITY OF VACUUM TUBE ELECTRODES INCLUDING AT LEAST A CONTROL GRID, SCREEN GRID AND PLATE ELECTRODE, SUPPORTING MEANS INCLUDING SUPPORTS AND ELECTRICAL LEADS FOR SUPPORTING SAID ELECTRODES ABOVE SAID CERAMIC STEM, A CERAMIC SPACER HAVING A PAIR OF ISOLATED METAL LAYERS ON ONE SURFACE THEREOF, TWO ADJACENT ONES OF SAID ELECTRODES BEING SECURED TO RESPECTIVE METAL LAYERS ON SAID CERAMIC SPACER, THE ELECTRICAL LEAD CONNECTED TO THE ONE OF SAID TWO ADJACENT ELECTRODES INTERPOSED BETWEEN THE REMAINING ELECTRODES OF SAID CONTROL GRID, SCREEN GRID AND PLATE ELECTRODE PASSING THROUGH SAID CERAMIC STEM IN THE RECESSED PORTION THEREOF AND COMING INTO ELECTRICAL CONTACT WITH SAID METAL LAYER ON SAID CERAMIC STEM, THE ELECTRICAL LEADS CONNECTED TO SAID REMAINING ELECTRODES PASSING THROUGH THE PORTION OF THE CERAMIC STEM ISOLATED FROM THE METAL LAYER THEREON. 